Productivity impact of drought tolerant maize varieties under rainfall stress in Malawi: A continuous treatment approach

Drought tolerant (DT) maize varieties have received massive support in sub-Saharan Africa because of their potential to protect smallholder farmers against drought-related maize yield losses. Using four waves of household farm panel data from six districts in Malawi, we examine the impact heterogeneity of this technology on maize productivity using a continuous treatment approach. We find strong evidence of positive correlation between maize yield and adoption of DT maize varieties. On average, an increase by one hectare in the area allocated to DT varieties increases maize yield by 547 Kg/ha representing a 44% increase from the average maize yield of 1,254 Kg/ha for our sample. Our findings give evidence that DT maize technology has potential to protect smallholder farmers against drought-related production losses. Policies that promote increased allocation of maize area to DT maize hold potential to enhance food security. Smallholder farmers especially in drought-prone areas should be encouraged to allocate at least one-third of the maize plot to DT varieties while breeders continue with the efforts of breeding a DT variety that is not only drought tolerant but also adapted to all weather conditions. More importantly, the government should ensure provision of timely ex ante weather information to guide farmers on decision-making with respect to maize varietal choices.publishedVersio

Targeting drought-tolerant maize varieties in southern Africa: a geospatial crop modeling approach using big data

Maize is a major staple food crop in southern Africa and stress tolerant improved varieties have the potential to increase productivity, enhance livelihoods and reduce food insecurity. This study uses big data in refining the geospatial targeting of new drought-tolerant (DT) maize varieties in Malawi, Mozambique, Zambia, and Zimbabwe. Results indicate that more than 1.0 million hectares (Mha) of maize in the study countries is exposed to a seasonal drought frequency exceeding 20% while an additional 1.6 Mha experience a drought occurrence of 10–20%. Spatial modeling indicates that new DT varieties could give a yield advantage of 5–40% over the commercial check variety across drought environments while crop management and input costs are kept equal. Results indicate a huge potential for DT maize seed production and marketing in the study countries. The study demonstrates how big data and analytical tools enhance the targeting and uptake of new agricultural technologies for boosting rural livelihoods, agribusiness development and food security in developing countries

The management of desmoid tumours at Groote Schuur Hospital: A retrospective review of current practice

Background: Desmoid tumours (DTs) are rare soft tissue tumours that do not metastasise but are locally aggressive. Management options are varied and the response to treatment can be unpredictable. Aim: The aim of this study was to describe the clinical presentation, management strategies and outcomes for adult patients who were treated for DT. Setting: The study was conducted at Groote Schuur Hospital in Cape Town, South Africa and all patients from 2003 to 2016 who presented with DT were included. Method: This was a retrospective review of records. Data collected included: demographics, DT-associated conditions, site and size of tumour, histological findings, treatment modalities, follow-up and outcomes. Results: Seventy patients with histologically confirmed DT were identified. The majority were women (86%) and 77% presented with a painless mass. The commonest site was the anterior abdominal wall (47%). Definitive surgery was performed in 46 (66%) patients, whereas 13 (19%) had definitive radiotherapy. Nine patients received adjuvant radiotherapy post-surgery for involved or close margins. Recurrence developed in 20% patients post-surgery. In the primary radiotherapy group, one patient had disease progression. Two patients with mesenteric DT died because of bowel obstruction. Conclusion: This retrospective review of patients affected by DT at a single centre demonstrates the rarity of the condition, the unpredictable natural history and the variety of treatment options available. Many of our findings are similar to other published studies, except the mean size of DT which was bigger. Treatment outcomes following surgery or radiotherapy seem acceptable, although study limitations are noted

Evaluation of multistress tolerant maize varieties for sustainable intensification in northern Guinea Savanna of north eastern Nigeria

Maize productivity is limited by multiple stresses in the savannas of West and Central Africa. Field trials were conducted in northern Guinea savanna of Nigeria in 2011 and 2012 to evaluate the performance of multi-stress tolerant maize varieties. Thirteen varieties including Local Check replicated three times were tested in randomized complete block design. Plant and ear heights were significantly higher for LNTP x LNP-WC3 and 2004 TZE-W DTSTRC4 than POOL 18-SR, 2009 TZE-W POP-STR, EVDT 99-W STR; and EVDT 2000-Y STRQPM, respectively. Striga count was significantly lower for EVDT 99-W STR and LNTP x LNP-WC3 than all the other entries. Days to 50% tassel and 50% silk were each significantly earlier for EVDT 99STR W-STR QPM, DT-W STR SYN, EVDT-99W STR and 2009 TZEW DT STR than the Local Check. Anthesis Silk Interval (ASI) was significantly lower for TZE COMP3 DT-WC2, 2009 TZEW DT STR, and EVDT 99-W STR than Local Check. Number of ears plant-1 was significantly higher for 2008 DTMA-Y STR than Local Check. Grain yield ha-1 was significantly superior for DT-Y STR SYN, 2008 DTMA-Y STR, 2004 TZE-W DTSTR C4, 2009 TZEW DT STR and EVDT 99-W STRQPM, respectively. Plant height was positively correlated with ASI and ear height, while ear height was positively associated with ears plant-1, days to 50% silk and 50% tassel. Grain yield ha-1 was positively correlated with ears plant-1, days to 50 % silk, days to 50% tassel and ear height, while ears plant-1 was negatively correlated with ear weight. Farmer selection criteria for acceptance of variety were in the order: Striga tolerance > nutrient value > drought tolerance > flour value > good taste > high yield > early maturity. The five varieties: DTY STR SYN, 2008 DTMA-Y STR, 2004 TZE-W DT STRC4, 2009 TZEW DT STR and EVDT 99-W STRQPM satisfied farmers criteria and were promising and thus nominated for on-farm demonstration and subsequent adoption in the region

Evaluation of multi-stress tolerant maize varieties for sustainable intensification in Northern Guinea Savanna of north eastern Nigeria

Maize productivity is limited by multiple stresses in the savannas of West and Central Africa. Field trials were conducted in northern Guinea savanna of Nigeria in 2011 and 2012 to evaluate the performance of multi-stress tolerant maize varieties. Thirteen varieties including Local Check replicated three times were tested in randomized complete block design. Plant and ear heights were significantly higher for LNTP x LNP-WC3 and 2004 TZE-W DT-STRC4 than POOL 18-SR, 2009 TZE-W POP-STR, EVDT 99-W STR; and EVDT 2000-Y STRQPM, respectively. Striga count was significantly lower for EVDT 99-W STR and LNTP x LNP-WC3 than all the other entries. Days to 50% tassel and 50% silk were each significantly earlier for EVDT 99STR W-STR QPM, DT-W STR SYN, EVDT-99W STR and 2009 TZEW DT STR than the Local Check. Anthesis Silk Interval (ASI) was significantly lower for TZE COMP3 DT-WC2, 2009 TZEW DT STR, and EVDT 99-W STR than Local Check. Number of ears plant-1 was sig¬nificantly higher for 2008 DTMA-Y STR than Local Check. Grain yield ha-1 was significantly superior for DT-Y STR SYN, 2008 DTMA-Y STR, 2004 TZE-W DTSTR C4, 2009 TZEW DT STR and EVDT 99-W STRQPM, respectively. Plant height was positively correlated with ASI and ear height, while ear height was positively associated with ears plant-1, days to 50% silk and 50% tassel. Grain yield ha-1 was positively correlated with ears plant-1, days to 50 % silk, days to 50% tassel and ear height, while ears plant-1 was negatively correlated with ear weight. Farmer selec¬tion criteria for acceptance of variety were in the order: Striga tolerance > nutrient value > drought tolerance > flour value > good taste > high yield > early maturity. The five varieties: DTY STR SYN, 2008 DTMA-Y STR, 2004 TZE-W DT STRC4, 2009 TZEW DT STR and EVDT 99-W STRQPM satisfied farmers criteria and were promising and thus nominated for on-farm demonstration and subsequent adoption in the region

Influence of future air pollution mitigation strategies on total aerosol radiative forcing

We apply different aerosol and aerosol precursor emission scenarios reflecting possible future control strategies for air pollution in the ECHAM5-HAM model, and simulate the resulting effect on the Earth's radiation budget. We use two opposing future mitigation strategies for the year 2030: one in which emission reduction legislation decided in countries throughout the world are effectively implemented (current legislation; CLE 2030) and one in which all technical options for emission reductions are being implemented independent of their cost (maximum feasible reduction; MFR 2030). We consider the direct, semi-direct and indirect radiative effects of aerosols. The total anthropogenic aerosol radiative forcing defined as the difference in the top-of-the-atmosphere radiation between 2000 and pre-industrial times amounts to -2.00 W/m2. In the future this negative global annual mean aerosol radiative forcing will only slightly change (+0.02 W/m2) under the "current legislation" scenario. Regionally, the effects are much larger: e.g. over Eastern Europe radiative forcing would increase by +1.50 W/m2 because of successful aerosol reduction policies, whereas over South Asia it would decrease by -1.10 W/m2 because of further growth of emissions. A "maximum feasible reduction" of aerosols and their precursors would lead to an increase of the global annual mean aerosol radiative forcing by +1.13 W/m2. Hence, in the latter case, the present day negative anthropogenic aerosol forcing could be more than halved by 2030 because of aerosol reduction policies and climate change thereafter will be to a larger extent be controlled by greenhouse gas emissions. We combined these two opposing future mitigation strategies for a number of experiments focusing on different sectors and regions. In addition, we performed sensitivity studies to estimate the importance of future changes in oxidant concentrations and the importance of the aerosol microphysical coupling within the range of expected future changes. For changes in oxidant concentrations caused by future air pollution mitigation, we do not find a significant effect for the global annual mean radiative aerosol forcing. In the extreme case of only abating SO2 or carbonaceous emissions to a maximum feasible extent, we find deviations from additivity for the radiative forcing over anthropogenic source regions up to 10% compared to an experiment abating both at the same time

The potential impact of the demographic transition in the Senegal-Gambia region of Sub-Saharan Africa on the burden of infectious disease and its potential synergies with control programs: the case of hepatitis B

Background Sub-Saharan Africa (SSA) continues to suffer high communicable disease burdens as its demographic transition (DT) proceeds. Although the consequent changes in population structures influence age-specific contact patterns relevant for transmission, the age distribution of immunity, and the disease burden, investigation of the potential of DT to affect infectious disease epidemiology in regions of SSA has hitherto been overlooked. With a substantial disease burden and complex epidemiology, hepatitis B virus (HBV) represents a prime example of an infection whose epidemiology may be significantly influenced by the DT. Methods An age-structured mathematical model for HBV in the Senegal and Gambia (SG) region was set within a demographic framework with varying vital rates mirroring the entire course of the DT there over 1850–2100, to investigate the effects of the DT on HBV epidemiology, with and without the combined action of vaccination. The model was run from its reconstructed ancien régime (old order) demo-epidemiologic equilibrium and calibrated against SG 1950 age-distribution estimates and Gambian pre-vaccination HBV age-prevalence data. Results The model, which reproduced well demographic and HBV age-prevalence data, predicted a complex transition of HBV epidemiology over the course of the DT. This included a prolonged epoch of expansion alongside population growth and rejuvenation until 1990–2000, followed by a dramatic retreat, mainly reflecting projected fertility decline during the twenty-first century. This transitional pattern was mostly explained by the underlying demographically driven changes in horizontal transmission resulting from the changes in the age structure of the population. During 2000–2150 the HBV burden is predicted to decline by more than 70% even in the absence of vaccination. Conclusions Demographic change alone may strongly affect HBV disease burden and shape HBV endemicity. The onset of the demographically driven decline in HBV prevalence, aligned with the expansion of HBV vaccination, forms a synergy potentially boosting effectiveness of control. Such a synergy currently appears to be presenting a “window of opportunity” facilitating HBV elimination which it would be important to exploit and which underlines the importance of taking demographic change into account when assessing the potential longer term impact of vaccination and other control measures